PILAS

The need for a pilot assistance system is based on the fact that in today’s cockpits a huge amount of more or less processed sensor information is presented to the pilot via different interfaces. The interpretation, deduction and decision of actions to avoid hazardous situations is for most information left to the pilot. Exceptions are systems like TCAS and GCAS which are able to deliver action directives, limited to their own system knowledge.

The aim of PILAS is to allow the application of new flight profiles in the context of future air traffic management, enabling the crew to perform more demanding operations than today without reducing safety margins. As a result today’s mission will benefit from increased overall safety.

The baseline is a future HEMS mission in adverse weather conditions. This mission would dramatically increase the workload with today available systems, as the pilot is asked to perform approaches to unknown landing sites in IMC whereas he has to

survey the surrounding traffic,

check the obstacle situation,

be aware of ground proximity and

avoid hazardous weather

The high workload is based on the interpretation of different information and understanding of the relationship between them to solve potential conflicts in new situations with unpredictable boundary conditions. New functions are required to reduce this workload in merging and interpreting the information of the different sources. This shall have the effect of increasing the pilot’s situation awareness to allow for fast decision making in case of detected conflicts. In some case it may be helpful to transfer the decision making process to the avionic system and to just present the results for acknowledgement to the pilot. For example the only solution for a specific conflict situation may be a modification in the flight path. The system in this case does not propose to launch a new planning, but presents the planning result to the pilot, asking for activation of the new flight path.

This conflict resolution capability requires artificial situation awareness inside the avionic system. All the information available for the pilot must be provided to the PILAS system. During the head down flight (e.g. in instrument meteorological conditions), the pilot interprets data delivered by the avionic systems, mainly visualised on the displays. For this phase sufficient data about the outside world have to be gathered. PILAS uses a variety of databases, updated if necessary via data link, and sensors to create a synthetic image of the helicopter’s situation. Precise positioning by the aid of satellite positioning systems and additional alerting devices guarantee safe flight.

The result of the interpretation, a kind of mental representation of the relevant situation, is then analysed for potential conflicts and actions are determined for to resolve them.

The resulting avionic system has in the end to satisfy certification aspects. The involved processes shall therefore be deterministic and the knowledgebase verifiable.

In adapting the knowledgebase, the amount of classes subjected to situation interpretation and the degree of allowed automation, the Pilot assistance system should be able to cope with different operational needs.

The institute of Flight Guidance participates to the project by implementing the module “Noise Abatement Planner (NAP)” which supports the pilot in making his flight less noisy by adapting the route and/or approach and departure flight procedures to the special needs of noise abatement.

The noise emmission on the ground will be reduced by application of noise abatement procedures during departures and approaches at helipads and helicopter guidance along noise minimized routes in the vicinity of helipads.

The noise abatement procedures (noise abatement approach and departure constraints) define the altitude and speed profile for approach and departure, which result in a reduction of blade vortex interaction (BVI) noise (Figure 1). Wind data at the helipad and helicopter performance data are taken into account by the NAP.

Further noise reduction at helipads can be achieved by selecting an appropriate approach/ departure noise abatement route leading along railways or motorways, over industrial areas or least populated areas while avoiding to fly over highly sensitive locations like schools or hospitals. These routes guide the helicopter quietly out of the helipad vicinity. Up to four noise abatement routes for approach and departure are predefined for the main wind direction and stored in the systems navigation database. The NAP assumes takeoff and landing in headwind conditions and selects one of the four noise minimized routes best fitting to the wind situation at the helipad.

Figure 2: Example of a Modified Noise Sensitive Area (MNS)

For the enroute range the NAP modifies the noise sensitive areas (Figure 2) which are predefined and stored in the systems airspace database. The Mission Planner requests these modified areas from the noise abatement planner by defining a start_of_leg_point, an end_of_leg_point and a corridor which defines the area in which all noise sensitive areas should be considered. These noise sensitive areas can be densely populated areas, nature protection or other areas (e.g. pilot defined).

The Noise Abatement Planner (NAP) is one of the planning modules of the PILAS Mission Planner (MP). The MP manages all the planning modules. It tasks the NAP to produce noise abatement constraints (waypoints, altitude, speed/time) suitable for the Trajectory Generator (TJG).